The present invention, in some embodiments thereof, relates to a device for inserting medical implants into tissue and, more particularly, but not exclusively, to a device for inserting soft tissue markers.
Soft tissue implants include markers that are used to mark the site of a biopsy or another surgical procedure or medical treatment, for defining the location of the procedure or treatment before it is performed, or for marking a location where the procedure or treatment was performed, for future follow up medical procedures. Soft tissue implants also include therapeutic implants, for example for brachytherapy. The implant, whether it is used as a marker or for another purpose, is often inserted using a device that comprises a hollow needle or other cannulus structure, with a sharpened end for penetrating to a desired location in the tissue, and with the implant loaded into a channel inside the cannulus. The device may or may not be part of an instrument that is also used for the surgery or biopsy. The device sometimes has an obstruction that prevents the implant from accidentally leaving the device before the operator of the device is ready to implant it, so that it can be positioned precisely, and means for removing or circumventing the obstruction, and inserting the implant into the tissue, when it is properly positioned. An example of such a device with an obstruction is shown in FIGS. 1A-1C, and described below.
U.S. Pat. No. 6,261,243, to Burney et al, describes a cannulus for inserting a soft tissue marker, with an opening in the side of the cannulus. A sliding cover prevents the marker from leaving the cannulus until the cannulus is properly positioned.
US Patent Application Publication No. 2004/0236213, to Jones et al, describes a device with a cannulus holding a soft tissue marker, and a plug made of wax covering an opening at the end. The marker is pushed from behind by a stylet, which pushes hard enough to push the plug out of the cannulus, allowing the marker to emerge.
A similar device is described in U.S. Pat. No. 7,247,160 to Seiler et al, but instead of pushing the marker and the plug forward out of the cannulus, the cannulus is pulled back, while using the stylet to hold the marker and plug in place. This breaks the plug free from the cannulus, leaving the marker and the plug is place in the tissue, and may allow more accurate placement of the marker than if the cannulus is held in place and the marker and plug are pushed forward.
U.S. Pat. No. 7,047,063, to Burbank, describes a device for inserting a marker into soft tissue, in which the marker is placed in a cannulus that has a closed petalled end. When the marker is pushed from behind by a stylet, the marker pushes open the petals at the end of the cannulus, allowing the marker to emerge.
U.S. Pat. No. 6,402,677, to Jacobs, describes a device for inserting brachytherapy seeds into soft tissue. The seeds are placed in a cannulus, which has an end that is partly blocked by an obstruction. A stylet pushes the brachytherapy seeds with enough force to go past the obstruction, and leave the cannulus.
Soft tissue markers, as well as brachytherapy implants, are sometimes formed in the shape of a helical coil. Such implants are described, for example, in U.S. Pat. Nos. 6,261,243 and 7,047,063, cited above, and in US Patent Application Publication No. 2004/0073107 to Sioshansi, as well as International Publication No. WO00/24332 to Cortese, and U.S. Pat. No. 6,371,904 to Sirimanne.